Buchko S J, Holley R A, Olson W O, Gannon V P, Veira D M
Department of Food Science, University of Manitoba, Winnipeg, Canada.
J Food Prot. 2000 Nov;63(11):1467-74. doi: 10.4315/0362-028x-63.11.1467.
Three groups of six yearling steers (three rumen fistulated plus three nonfistulated) fed one of three different grain diets (85% cracked corn, 15% whole cottonseed and 70% barley, or 85% barley) were inoculated with 10(10) CFU of Escherichia coli O157:H7 strain 3081, and the presence of the inoculated strain was followed in the rumen fluid and feces for a 10-week period. E. coli O157:H7 was rapidly eliminated from the rumen of the animals on all three diets but persisted in the feces of some animals up to 67 days after inoculation, suggesting that the bovine hindgut is the site of E. coli O157:H7 persistence. A significant difference existed in the levels of E. coli O157:H7 shed by the animals among diets on days 5, 7, 49, and 63 after inoculation (P < 0.05). No significant difference was found between the levels shed among diets on days 9 through 42 and on day 67 (P > 0.05). The number of animals that were culture positive for E. coli O157:H7 strain 3081 during the 10-week period was significantly higher for the barley fed group (72 of 114 samplings) as opposed to the corn fed group (44 of 114 samplings) (P < 0.005) and the cottonseed and barley fed group (57 of 114 samplings) (P < 0.05). The fecal pH of the animals fed the corn diet was significantly lower (P < 0.05) than the fecal pH of the animals fed the cottonseed and barley and barley diets, likely resulting in a less suitable environment for E. coli O157:H7 in the hindgut of the corn fed animals. E. coli O157:H7 strain 3081 was present in 3 of 30 (corn, 1 of 10; cottonseed, 1 of 10; barley, 1 of 10) animal drinking water samples, 3 of 30 (corn, 1 of 10; cottonseed, 0 of 10; barley, 2 of 10) water trough biofilm swabs, 5 of 30 (corn, 0 of 10; cottonseed, 2 of 10; barley, 3 of 10) feed samples, and 30 of 30 manure samples taken from the pens during the entire experimental period. Mouth swabs of the steers were also culture positive for E. coli O157:H7 strain 3081 in 30 of 180 samples (corn, 7 of 60; cottonseed, 4 of 60; barley, 19 of 60) taken during the 10-week period. Minimizing environmental dissemination of E. coli O157:H7 in conjunction with diet modification may reduce numbers of E. coli O157:H7-positive cattle.
将三组（每组六头一岁公牛，其中三头有瘤胃瘘管，三头没有）分别饲喂三种不同谷物日粮（85%破碎玉米、15%全棉籽和70%大麦，或85%大麦）的牛，接种10¹⁰CFU的大肠杆菌O157:H7菌株3081，并在瘤胃液和粪便中追踪接种菌株10周。在所有三种日粮的牛瘤胃中，大肠杆菌O157:H7均迅速被清除，但在一些动物的粪便中，接种后长达67天仍有该菌存在，这表明牛的后肠是大肠杆菌O157:H7持续存在的部位。接种后第5、7、49和63天，不同日粮组动物排出的大肠杆菌O157:H7水平存在显著差异（P<0.05）。在接种后第9至42天和第67天，不同日粮组排出的大肠杆菌O157:H7水平之间未发现显著差异（P>0.05）。在10周期间，饲喂大麦组的动物中，大肠杆菌O157:H7菌株3081培养阳性的数量（114次采样中有72次）显著高于饲喂玉米组（114次采样中有44次）（P<0.005）和饲喂棉籽和大麦组（114次采样中有57次）（P<0.05）。饲喂玉米日粮的动物粪便pH值显著低于饲喂棉籽和大麦以及大麦日粮的动物（P<0.05），这可能导致在饲喂玉米的动物后肠中，大肠杆菌O157:H7的生存环境不太适宜。在整个实验期间采集的30份动物饮用水样本中，有3份（玉米组10份中有1份；棉籽组10份中有1份；大麦组10份中有1份）检测到大肠杆菌O157:H7菌株3081；30份水槽生物膜拭子样本中，有3份（玉米组10份中有1份；棉籽组10份中有0份；大麦组10份中有2份）检测到该菌；30份饲料样本中，有5份（玉米组10份中有0份；棉籽组10份中有2份；大麦组10份中有3份）检测到该菌；30份牛舍粪便样本均检测到该菌。在10周期间采集的180份公牛口腔拭子样本中，有30份（玉米组60份中有7份；棉籽组60份中有4份；大麦组60份中有19份）检测到大肠杆菌O157:H7菌株3081。结合日粮调整，尽量减少大肠杆菌O157:H7在环境中的传播，可能会减少大肠杆菌O157:H7阳性牛的数量。
